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Alkane

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Alkane

The aliphatic hydrocarbons which have carbon-carbon single bond are called alkane.

The general formula of alkane is CnH2n+2, where n = number of hydrogen

E.g. methane (CH4), ethane (C2H6) etc.

Word root Alkane Formula

C1 → Meth Methane CH4

C2 → Eth Ethane C2H6

C3 → Prop Propane C3H8

C4→ But Butane C4H10

C5 → Pent Pentane C5H12

C6 → Hex Hexane C6H14

C7 → Hept Heptane C7H16

C8 → Oct Octane C8H18

C9 → Non Nonane C9H20

C10 → Dec Decane C10H20

The suffix of the alkane is (ane).

Alkyl

The replacement or loss of one hydrogen from the alkane is called alkyl.

It is denoted by (-R), where –R indicates alkyl group.

The general formula of the alkyl is CnH2n+1.

Nomenclature

CH4 → methane

C2H6 → Ethane

CH3 - CH3 → Ethane

C3H8 → Propane

CH3 - CH2 - CH3 → n-propane

CH3 - CH2 - CH2 - CH2 - CH3 → n-pentane

IUPAC Nomenclature

Prefix + word root + primary suffix + secondary suffix

3-methyl hexane
source:www.kentchemistry.com
Fig: 3-methyl hexane

Prefix → 3-methyl

Word root → Hex

Primary suffix → ane

Therefore the IUPAC name is 3-methyl hexane

octamethane
source:http://www.fccj.info/
Fig: octa-methane

Prefix → 4- ethyl 4,6- methyl

Word root → Oct

Primary suffix → ane

Prefix

-CH3 → Methyl

-C2H5 → Ethyl

-Cl → Chloro

-Br → Bromo

-I → Iodo

-F → Fluoro

-CO → Keto

-CHO → Aldo

-NH2 → Amino

-OH → Hydroxyl

-CN → Cyano

-NO2 → Nitro

1-chloro 4-iodo 2-methane pentane
source:http://www.docbrown.info/
Fig: 1-chloro 4-iodo 2-methane pentane

3-bromo 2, 4, 4 –trichloro 3-iodo 2-methyl hexane

Note:

R-X → alkyl halide or haloalkane

X = Cl, Br, I, F

CH3-Cl

Chloromethane Or Methyl Chloride

CH3-CH2-CH2-Br

Bromo Propane Or Propyl bromide

Isomerism

The organic compounds having same molecular formula but different structural formula are called isomers and the phenomenon is called isomerism.

From butane isomers, occur i.e. methane, ethane, propane does not have isomers.

E.g. pentane (C5H12)

isomers of pentane
source:www6.miami.edu
Fig:isomers of penta

Functional group

The structure of the particular family of an organic compound is called functional group.

It determines the properties of the organic compound.

S.n

Class

General formula

Functional group

Secondary suffix

1

Hydrocarbon

a.

Alkane

CnH2n+2

b.

Alkene

CnH2n

c.

Alkyne

CnH2n-2

2

Alkyl halide

R-X

-X

3

Alcohol

R-OH

-OH

Ol

4

Ether

R-O-R

-O-

ether

5

Aldehyde

R-COH

-COH

al

6

Ketone

R-CO-R

-CO-

one

7

Carboxylic acid

R-COOH

-COOH

oic acid

8

Ester

R-COO-R

-COO-

ester

9

Amide

R-CONH2

-CONH2

amide

10

Amine

R-NH2

-NH2

amine

11

Cyanide

R-CN

-CN

nitril

Priority order: COOH > CHO > CO > OH

Alcohol

Structure: R - OH

Functional group: -OH

Secondary suffix: ol

Alkane – e + ol → alkanol

E.g. CH3 - CH = CH - CH2 - OH → but-2-ene-1-ol

CH3 - CH2 - CH2 - OH → Propanol

Aldehyde

Structure: R - CHO

Functional group: -CHO

Secondary suffix: al

Alkane – e + al → alkanol

E.g. CH3 - COH → Ethanal

CH3 - CH2 - COH → Propanal

H - CHO →Methanal

Note:

OCH3 → Methoxy

OC2H5 → Ethoxy

OC3H7 → Propoxy

Carboxylic acid

Structure: R - COOH

Functional group: -CHO

Secondary suffix: oic acid

Alkane – e + oic acid → alkanoic acid

E.g. H - COOH → Methanoic acid

CH3 - COOH → Ethanoic acid

CH3 - CH2 - COOH → Propanoic acid

CH3 - CH2 - CH2 - COOH →Butanoic acid

Ketone

Structure: R – COO - R

Functional group: -COO-

Secondary suffix: one

Alkane – e + one → alkanone

E.g.

propan-2-one
source:http://i246.photobucket.com/
Fig: propan-2-one

→ Propane – e + one i.e propanone or propan – 2 – one

Amine

Structure: R - NH2

Functional group: -NH2

Secondary suffix: amine

Alkane – e + amine = alkanamine

E.g. CH3-NH2 → Methenamine

CH3 - CH2 - NH2 → Ethanamine

Ether

Structure: R - O - R

Functional group: - O -

Secondary suffix: Ether

E.g. CH - O - CH3 → dimethyl ether/methoxy methane

CH3 - CH2-O - CH3 →methoxy ethane

Cyanide

Structure: R - CN

Functional group: -CN

Secondary suffix: nitril

E.g. CH3 - CN →methyl cyanide/ethane nitril

CH3 - CH2 - CH2 - CN →butane nitril/propyl cyanide

Amide

Structure: R - CONH2

Functional group: -CONH2

Secondary suffix: amide

Alkane – e + amide = alkanamide

E.g.

O

‖

CH3 - C - NH2 → Ethanamide

propanamide
Propanamide

Reference

Pulse, Tracy. Introduction to chemistry. u.s.a: flexbook, 2010.

Pathak, Sita Karki. The Text Book of Chemistry. Kathmandu: Vidhyarthi Pustak Bhandar, 2012.



  • The aliphatic hydrocarbons which have carbon-carbon single bond are called alkane.
  • The replacement or loss of one hydrogen from an alkane is called alkyl.
  • The organic compounds having same molecular formula but different structural formula are called isomers and the phenomenon is called isomerism.
  • The structure of the particular family of an organic compound is called functional group.
.

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